Glycopeptide antibiotics can be classified in four groups based on their chemical structure:                Group I (or the vancomycin type) has aliphatic amino acids at positions 1 and 3;        Group II (or the avoparcin type) has aromatic amino acid residues at positions 1 and 3;        Group III (or the ristocetin type) is similar to group II but for an ether linkage joining the aromatic amino acids at positions 1 and 3; and        Group IV (or the Teicoplanin type) has the same amino acid arrangement as group m plus a fatty acid residue attached to the amino sugar.(Yao, R. C. and Crandall, L. W., Glycopeptides, Classification, Occurrence, and Discovery in Glycopeptide antibiotics, ed. Nagarajan, R., Marcel Dekker, Inc., N.Y, N.Y., Chapter 1, pp. 1-27 (1994)).        
Teicoplanin is a glycopeptide antibiotic produced by Actinoplanes teicomyceticus and was discovered during a scientific research program aiming to find new molecules of microbial origin that inhibited bacterial cell wall synthesis. (Goldstein, B. et al, Teicoplanin in Glycopeptide Antibiotics, ed. Nagarajan, R., Marcel Dekker, Inc., N.Y, N.Y., Chapter 8, pp. 273-307 (1994)). It was first described in 1978 and ten years later it was introduced into clinical practice in Italy. (Parenti, F. et al, J. Chemotherapy, Vol. 12, pp. 5-14, (2000)).
Teicoplanin shares many chemical and microbiological characteristics with vancomycin, but it possesses higher activity against many Gram-positive bacteria and is less nephrotoxic. (Parenti, supra; Janknegt, R., (1991), Teicoplanin in Perspective, Pharmaceutisch Weekblad Scientific Edition, 13: 153-160).
The molecular structure of Teicoplanin is depicted in FIG. 1. Like all glycopeptide antibiotics, Teicoplanin contains a core linear heptapeptide, in which five of the seven amino acids are common to all the members of its group. The remaining two (positions 1 and 3) are linked together by an ether bond. (Yao, supra). Three sugar moieties are attached to the aryl groups of amino acids 7, 6 and 4, namely a D-mannose, an N-acetyl-D-glucosamine and an N-acyl-D-glucosamine, respectively. These sugars have no biological activity in vitro, but have been found to impart different pharmacokinetic properties. (Reynolds P. E., Eur. J. Clin. Microbiol. Infect. Dis., Vol. 8, No. 11, pp. 943-950, (1989)).
Teicoplanin comprises different components, including five closely related molecules denoted Teicoplanin A2-1 (TA2-1) to Teicoplanin A2-5 (TA2-5), which differ only in the nature of the acyl moiety (C10 and C11 fatty acids); RS-1 to RS-4; a more polar component Teicoplanin A3-1 (TA3-1), which lacks the N-acyl-D-glucosamine residue and Teicoplanin TA3-2, which also lacks the D-mannose group. Substitution of the sugar residues with hydrogens results in the core aglycone, which is considered as a Teicoplanin A3 component. The molecular structures of the different components are shown in FIG. 2 herein.
U.S. Pat. No. 4,239,751 to Coronelli et al. describe isolation of different Teicoplanin components. Also illustrated in Table IV therein is that TA3 has a lower antibiotic activity than TA2.
U.S. Pat. No. 4,994,555 to Panzone et al. describes recovery of Teicoplanin from aqueous solutions from fermentation broths. Panzone et al. further describes “[a]s employed in its biological application Teicoplanin essentially consists of factor A2 (T-A2) accompanied by minor amount of factor A3 (T-A3)”. (Column 2, lines 51-53).
Coronelli et al.: “Teicoplanin: Chemical, Physico-chemical and Biological Aspects”, in Farmaco, Edizione Scientifica (1987), 42 (10), 767-86, state that a typical teicoplanin production batch contains no more than 12% TA3-1 and about 10% water.
Malabarba et al.: “Teicoplanin, Antibiotics from Actinoplanes Teichomyceticus nov. sp, Journal of Antibiotics 1984 Japan, vol. 37, no. 9, 1984, 988-999, states that they, starting from teicoplanin, prepared a crude material (intermediate composition) which contained 74% TA3-1 and 16% TA3-2 (HPLC).
TARGOCID is a commercial Teicoplanin product from Aventis Pharma.